Method of making two-piece paper cups



Sept? 1967 V D. w. BAUMGARTNER I I 3,342,1 13

METHOD OF MAKING TWOPIECE PAPER'CUPS Filed March 26, 1965 2 Sheets-Shet 1 AmRNEY 419- 3 0. w. sAume z r J g P 19, 1957 D. w. BAUMGARTNER 3,342,113

METHOD OF MAKING TWOPIECE PAPER CUPS Filed March 26, 1965 I 2 Sheets-Sheet Z INVENTOR. D. W. BAUMGARTNER United States Patent 3,342,113 METHOD OF MAKING TWO-PIECE PAPER CUPS Donald W. Baumgartner, 4740 N. Bartlett Ave., Milwaukee, Wis. 53211 Filed Mar. 26, 1965, Ser. No. 442,909 4 Claims. (Cl. 93-391) This invention relates generally to two-piece paper cups of the type having a frusto-conical side wall which is Wrapped around a disc-like bottom which has a short downwardly extending flange, and the lower end of the side Wall is then bent around the flange to form a seal around the bottom of the finished cup. More specifically, the invention relates to a method of forming the flange on the disc-like bottom prior to wrapping of the side wall therearound.

The present invention finds utility when making cups on the type of machines shown, for example, in the U.S. Patent No. 2,942,530, issued on June 28, 1960, to Bodendoerfer and entitled Blank Wrapping Mechanism for Frusto-Conical Cup Making Machines. Reference may be had to that patent if deemed to be necessary or desirable, but it is believed suflicient to say that a disc-like bottom blank is formed with a generally longitudinally formed flange, and then the blank held on the end of a frusto'conical mandrel by suction with the flange extending generally away from the end of the mandrel. A side wall blank is then Wrapped around both the mandrel and the bottom blank.

As the turret carrying these mandrels rotates, subsequent operations at different stations of the machine bend the end of the side wall around the flange, smooth the joint so formed, and tightly press it into final form. One example of a mechanism for performing this final finishing operation on the bottom joint is shown in the U.S. Patent No. 2,942,531, issued on June 28, 1960, to Loeser et al. and entitled Bottom Expander for Paper Cups. The seam of the side wall may be glued and sealed, or if a thermoplastic material is used, the side seam of the cup may be sealed by apparatus such as shown in the U.S. Patent No. 3,134,307, issued on May 26, 1964.

These prior art devices have proved to be generally satisfactory. Sometimes, however, the side wall blank is prevented from being wrapped tightly around the mandrel, and it fails to be formed into the precise form intended. As a result of this improper wrapping, a cup that leaks at the bottom joint isproduced. One of the main reasons for the failure of the side wall blank to be wrapped tightly and accurately around the mandrel and around the flanged disc-like or circular bottom is that the bottom flange prevents or resists such wrapping.

It is accordingly an object of the present invention to provide a method for completely forming thebottom flange before wrapping of the side wall so that the bottom offers no resistance to the tight and accurate wrapping of the side wall blank around the mandrel and around the bottom itself. The result is the more uniform production of leak-proof cups. More specifically, the invention provides that the flange of the circular bottom blank is first partially formed by pushing a circular blank through a die such as a cylinder, placing it on a mandrel, and then reforming the flange at such an angle that it does not protrude radially beyond the periphery of the mandrel and thereby interfere with the tight Wrapping of the side wall blank around the mandrel.

These and other objects and advantages of the present invention will appear later as this disclosure progresses, reference being had to the accompanying drawings, in which:

FIGURE 1 is a fragmentary, sectional view through the conventional mechanism of a station in a cup-making machine where the circular bottom blank is first partially formed;

FIGURE 2 shows the bottom blank on the mandrel, as in FIGURE 1, but shortly after the blank has been pushed from the preliminary forming cylinder;

FIGURE 3 is a fragmentary, sectional view through the bottom reformer station mechanism in accordance with the present invention;

FIGURE 4 is a view similar to FIGURE 2 but showing the blank after it has been reformed;

FIGURE 5 shows a side wall wrapped around the mandrel and cup bottom of FIGURE 4; and

FIGURE 6 shows the mechanism at the station where that end portion of the side wall which protrudes axially beyond the cup bottom is folded or bent around the bottom flange.

Referring in greater detail to FIGURE 1 of the drawings, a rotatable turret T of the cup-forming machine carries a series of circumferentially spaced mandrels M (only one shown) from station to station during the cupforming operation in the conventional manner. The station shown in FIGURE 1 is where a circular bottom blank B is fed through a slot 7 in the housing 8. The blank then falls downwardly across the bore 9 with its periphery held in the slot 10 of the stationary or fixed sleeve 11. A plunger 13, which is actuated in the known manner, then moves in the direction indicated by the arrow to force the disk through the bore 9, thus forcing the periphery edge of the disk to fold into a flange 14. In other words, the original size of the bottom blank is larger than the bore 9, and the operation just described is in the nature of a drawing operation wherein the outer portion of the blank is formed into a flange 14 as indicated. The plunger places the partially formed bottom blank on the flat end 15 of the mandrel M where it is held by vacuum means in the conventional manner. The mandrel M is then rotated to the next station.

FIGURE 2 shows the shape of the bottom blank after it leaves the previously described station. It will be noted that the flange has sprung outwardly beyond the periphery of the mandrel.

FIGURE 3 shows the bottom reforming mechanism to which the partially formed bottom blank is next presented, and it will be noted that the flange 14 is guided by the internal, frusto-conical surface 18 and against the roller 19 of the reformer mechanism. The roller 19 is of a smaller diameter than the left end (as viewed in the figure) of the internal tapered surface 18, and is carried on an arm 20 which is pivoted at 21, and an axially slidable cam 22 forces the abutting roller 23 on the arm 20 and causes the forming roller 19 to be shifted radially so that it tightly squeezes the flange 14 against the internal surface 18. As the roller rotates around its own axis and also bodily around the surface 18, it reforms the flange 14 by tightly pressing it against the surface 18 so as to remove the elastic memory or resiliency from the flange, more particularly, from the junction of the flange 14 and cup bottom proper. It will be noted that the angle of deformation is greater than the angle of the taper on the mandrel; in other words, the flange 14 is bent radially inwardly beyond the outer diameter of the cup bottom corner 25. In this manner, it is assured that the flange 14 lies within the periphery of the mandrel M. It is s'uflicient in most cases that the flange 14 is bent inwardly by the roller sufficiently so that it does not extend beyond the periphery of the mandrel.

FIGURE 4 then illustrates the relative shape of the cup bottom as compared to the mandrel and after they have left the reforming station shown in FIGURE 3.

FIGURE 5 shows the mandrel and cup bottom after they have left the wrapping station where a side wall 30 has been wrapped around both the mandrel and the cup bottom. It will be noted that the side wall has been wrapped tightly around both so no space exists between the periphery of the mandrel and the side wall. If this wrapping operation had taken place while the cup bottom was in the condition shown in FIGURE 2, the flange of the cup bottom occasionally would prevent the side wall from being wrapped tightly around the mandrel, thus producing a loose or open bottom joint.

FIGURE 6 shows the bottom folding station where that axially extending portion 31 of the side wall, which protrudes beyond the bottornmost edge of the flange of the cup bottom, is folded around the edge of the flange and back under the cup bottom by means of the conventional rotating flange folding tool 32.

Subsequent operations then expand and finish the bottom joint, such as the station shown in FIGURE 4 of the US. Patent No. 2,942,531, previously referred to.

RESUME By means of the present invention, a method of forming a two-piece paper cup has been provided in which the cup bottom is fully formed prior to wrapping of the side wall therearound. As a result, the cup bottom can remain accurately centered on the mandrel bottom because the side wall does not contact the extending flange to shift the bottom on the mandrel end. Furthermore, the bottom flange does not act to resist or prevent the side wall from being wrapped tightly around both the mandrel and cup bottom.

The invention has proved to be hightly satisfactory in assuring the uniform production of leak-proof, two-piece paper cups.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claming the subject matter which is regarded as the invention.

I claim:

1. A method of making a two-piece paper cup of the frusto-conical, flat-bottom type on a frusto-conical mandrel having a flat end, said method comprising, forming an annular flange around a paper circular bottom blank, reforming said flange by pressing it further radially inwardly so that it does not extend radially beyond the periphery of the mandrel, wrapping a side wall blank tightly around the bottom with a portion of said side wall protruding axially beyond the bottom flange, and folding said portion over said flange.

2. A method of making a two-piece paper cup of the frusto-conical, flat-bottom type on a frusto-conical mandrel having a flat end, said method comprising, forming an annular flange around a paper circular bottom blank, placing said blank on the flat end of said mandrel with said flange extending outwardly of said mandrel, reforming said flange by pressing it radially inwardly so that it does not extend radially beyond the periphery of the mandrel, wrapping a side wall blank tightly around the mandrel and bottom with a portion of said side wall protruding axially beyond the bottom flange, and folding said portion over said flange.

3. A method of making a two-piece paper cup of the frusto-conical, flat-bottom type on a 'frusto-conical mandrel having a flat end, said method comprising, forming an annular flange around a paper circular bottom blank by drawing said circular blank through a cylinder so as to partially form said flange which springs outwardly beyond the periphery of the rest of the partially formed bottom when released from said cylinder, reforming said flange by pressing it further radially inwardly so that it does not extend radially beyond the periphery of the mandrel, wrapping a side wall blank tightly around the bottom with a portion of said side wall protruding axially beyond the bottom flange, and folding said portion over said flange.

4. A method of making a two-piece paper cup of the frusto-conical, flat-bottom type on a frusto-conical mandrel having a flat end, said method comprising, forming an annular flange around a paper circular bottom blank by drawing said circular blank through a cylinder so as to partially form said flange which springs outwardly beyond the periphery of the rest of the partially for-med bottom when released from said cylinder, placing said partially formed bottom on the flat end of said mandrel with said flange extending outwardly of said mandrel, reforming said flange while on said mandrel and by pressing it further radially inwardly with a rotatable roller that travels bodily and circumferentially around the inside of the flange so that it does not extend radially beyond the periphery of the mandrel, wrapping a side wall blank tightly around the mandrel and bottom with a portion of said side wall protruding axially beyond the bottom flange, and folding said portion over said flange.

References Cited UNITED STATES PATENTS BERNARD STICKNEY, Primary Examiner. 

1. A METHOD OF MAKING A TWO-PIECE PAPER CUP OF THE FRUSTO-CONICAL, FLAT-BOTTOM TYPE ON A FRUSTO-CONICAL MANDREL HAVING A FLAT END, SAID METHOD COMPRISING, FORMING AN ANNULAR FLANGE AROUND A PAPER CIRCULAR BOTTOM BLANK, REFORMING SAID FLANGE BY PRESSING IT FURTHER RADIALLY INWARDLY SO THAT IT DOES NOT EXTEND RADIALLY BEYOND THE PERIPHERY OF THE MANDREL, WRAPPING A SIDE WALL BLANK TIGHTLY AROUND THE BOTTOM WITH A PORTION OF SAID SIDE WALL PROTRUDING AXIALLY BEYOND THE BOTTOM FLANGE, AND FOLDING SAID PORTION OVER SAID FLANGE. 